Hi Gunjesh,
In short, Microsoft.Xrm.Sdk is used to interact with entity, and it is the main library we use for Dynamics.
Here are some most used interface and classes from Xrm.Sdk:
IOrganizationService(I), Entity, EntityCollection, EntityReference, IPluginExecutionContext(I)
While Microsoft.Crm.Sdk is less used, at least from my using experience. According to documentation, it seems that we could get some organization level information with the namespace.
However, another similar namespace with longer name Microsoft.Crm.Sdk.Messages is used more than Microsoft.Crm.Sdk, it has all built-in actions of Dynamics such as QualifyLeadRequest.
(Actually both of these two namespaces belong to Microsoft.Crm.Sdk.Proxy.dll assembly, so I think the comparison should be made between Microsoft.Crm.Sdk.Proxy.dll and Microsoft.Xrm.Sdk.dll instead.)
Regards,
Clofly
